Polybutylene terephthalate resins (hereafter also referred to as “PBT resins”) have a high heat distortion temperature and exhibit excellent electrical properties, mechanical properties, weather resistance and chemical resistance and the like, and are consequently widely used as engineering plastics in a variety of applications, including electrical and electronic components, and vehicle components and the like.
Components such as relays, switches and connectors that are used in the vicinity of power sources of electrical and electronic components require tracking resistance in order to ensure adequate safety from the possibility of ignition associated with electrical loading. For this reason, improvements have also been made to PBT resin compositions to improve their tracking resistance.